linux-kernel - Re: [PATCH v1 2/3] Mark functions with the latent

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Message-ID: <CAGXu5jJ+e0CX3QBm-XWYJ6ViCuX-Pcbvm-he7FBqYJBScw1kPA@mail.gmail.com>
Date:	Tue, 24 May 2016 13:55:51 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Emese Revfy <re.emese@...il.com>
Cc:	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>,
	PaX Team <pageexec@...email.hu>,
	Brad Spengler <spender@...ecurity.net>,
	Michal Marek <mmarek@...e.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Masahiro Yamada <yamada.masahiro@...ionext.com>,
	linux-kbuild <linux-kbuild@...r.kernel.org>,
	"Theodore Ts'o" <tytso@....edu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-MM <linux-mm@...ck.org>, Jens Axboe <axboe@...nel.dk>,
	Al Viro <viro@...iv.linux.org.uk>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	bart.vanassche@...disk.com, "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v1 2/3] Mark functions with the latent_entropy attribute

On Tue, May 24, 2016 at 1:45 PM, Emese Revfy <re.emese@...il.com> wrote:
> On Tue, 24 May 2016 10:16:09 -0700
> Kees Cook <keescook@...omium.org> wrote:
>
>> On Mon, May 23, 2016 at 3:16 PM, Emese Revfy <re.emese@...il.com> wrote:
>> > +#ifdef CONFIG_MEMORY_HOTPLUG
>> > +#define add_meminit_latent_entropy
>> > +#else
>> > +#define add_meminit_latent_entropy __latent_entropy
>> > +#endif
>> > +
>> >  /* These are for everybody (although not all archs will actually
>> >     discard it in modules) */
>> > -#define __init         __section(.init.text) __cold notrace
>> > +#define __init         __section(.init.text) __cold notrace __latent_entropy
>> >  #define __initdata     __section(.init.data)
>> >  #define __initconst    __constsection(.init.rodata)
>> >  #define __exitdata     __section(.exit.data)
>> > @@ -92,7 +98,7 @@
>> >  #define __exit          __section(.exit.text) __exitused __cold notrace
>> >
>> >  /* Used for MEMORY_HOTPLUG */
>> > -#define __meminit        __section(.meminit.text) __cold notrace
>> > +#define __meminit        __section(.meminit.text) __cold notrace add_meminit_latent_entropy
>> >  #define __meminitdata    __section(.meminit.data)
>> >  #define __meminitconst   __constsection(.meminit.rodata)
>> >  #define __memexit        __section(.memexit.text) __exitused __cold notrace
>>
>> I was confused by these defines. :) Maybe "add_meminit_latent_entropy"
>> should be named "__memory_hotplug_only_latent_entropy" or something
>> like that?
>
> I think the plugin doesn't cause a significant slowdown when CONFIG_MEMORY_HOTPLUG is enabled so I would rather always add the __latent_entropy attribute to __meminit.

That seems fine to me. :)

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security